ok actual model number of honeywell model is rthl 2510c it is a 7 day programmable model..

do you have gas heat ? heat pump? more info needed.

Ok members found out problem regarding thermostat...when the batteries are going out on a electronic thermostat like the honeywell model i purchased. wen u take it off wall to replace batteries. i had to leave unit off wall overnite almost like it had to reset. because when i finally put it back on wall it started to work just fine............SO FYI make sure unit is turned off before removing to replace batteries......otherwise the unit goes haywire..................

well I am not sure what your problem was but that wasn't it. I replace batteries in thermostats usually a couple times a day in customers houses. problem will most likely surface again.